Lubrication and cooling of antifriction bearings



April 28, 1942. O MUELLER 2,280,965

LUBRICATION AND COOLING OF ANTIFRICTION BEARINGS Original Filed Oct. 7,1939 INVENTOR 5/06 0 Mae //e/'.

' ATTORNEY Patente d Apr. 28, 1 942 LUBRICATION AND COOLING F ANTI-FRIC'I'IDN BEARINGS Erich 0. Mueller, Irwin, Pa., assignor to Westinp- Ihouse Electric & Manufacturing Company, East Pittsburgh, Pa., acorporation of Pennsylvania Original application October 7, 1939, SerialNo. 298,463. Divided and this application March 9, 1940, Serial No.323,210

4 Claims.

This application is a division of my copending application Serial No.298,463, filed October 7, 1939, the claims of which are directed to alubrication arrangement of general application in high-speedantifriction bearings.

My invention relates to bearings for electric motors or other machines,and it has particular relation to bearings for machines running at veryhigh speeds, such as speeds of from 1&00-0 R. P. M. to 43,000 R. P. M.,such as high-frequency induction. motors.

Cine of the objects of my invention is to produce adequate lubricationfor the ball and roller bearings of lilo-cycle, 24,000 R. P. M1,,aircraft motors which are required to run at extremely changeableoutside temperatures, and to run continuously for three weeks withoutthe addition of any lubricant and with the machine mounted in anyconceivable position. These conditions are very severe. Grease could notbe used for the lubricant, because there is no available grease thatwill work at the required temerature-range of -30 C. to +80 6., andbecause of the well-nigh impossibility of packin the bearings with justprecisely the right amount of grease, while allowing for a reasonableefllciency and good starting conditions of highspeed motors with lowhorsepower ratings. Oil lubrication, applied in the ordinary way withtree oil present in the bearing-enclosures, would also not solve theproblem, since the bearing-seals could not be made so that tree oilwould not run out, with the motors turned in any position, and alsobecause any appreciable amount of oil, in

the bearings pr0per,. would cause excessive churning and heating of theoil, driving practically all of the oil off, in vapor form, immediatelyafter the starting of the motor.

The amount of oil which is needed in the lubrication oi antiirictionbearings is very small just enough to maintain an oil-film. Experimentshave shown that a drop of oil will maintaln the oil-film for severalhours, particularly where means are provided for supplying said oil inthe form of an oil-vapor or mist which will permeate the space betweenthe inner and outer races of the antifrlctlon bearing proper, suitableoil-seals being provided for retaining the oilvapor or mist within thebearing-enclosure inany possible operating-position oi the apparatus.

The principal object of my present invention is to provide a combinedbearing and ventilating assembly, in which a fan is utilized forproducing a movement of air within the machine-enclosure, forventilating purposes, and in which the fan- (ill. 171-252) suction inthe vicinity of the bearing is broken up by means of vent-holes andseals.

With the foregoing and other objects in view, my invention consists inthe parts, structures, machines, assemblies and methods hereinafterdescribed and claimed, and illustrated in the accompanying drawing, thesingle figure oi which is a longitudinal sectional view of a motorembodying my invention in a preferred form of construction. j

The illustrated motor is a iGQ-cycle, 214,000 R. P. M. aircraft motorcomprising a stationary primary-winding member l and a squirrel-cagerotor-member 2 mounted in cooperative relationship, the stator-member ibeing mounted within an enclosing machine-frame or casing 3, and therotor-member 2 being mounted on a shaft 4. The rear end of the shaft 4extends outside of the casing 3, as indicated at 5, to drive any desiredmechanism. The opposite, or front, end of the shaft is shown as beingsupported and aligned. by a light series ball bearing 0, although itmight be a roller bearing designed to take thrust. The illustratedballbearing .5 comprises inner and outer races 1 and 8, respectively, with aplurality of balls 8 therebetween. The rear, or driving, end of theshaft 4 is mounted in a light series roller bearing H comprising innerand outer races l2 and I3, respectively, with a plurality of rollers I4therebetween. The rearend roller-bearing it permits free longitudinalexpansion of the shaft 4, and takes care of manufacturing toleranceslengthwise.

The ball bearing 6 at the front end of the machine is mounted in a steelbearing-cap it, which is to say, that the outer race 8 is pressed withina suitable seat H in the bearing-cap It, the inner race I being pressedupon the shaft 4. The bearing-cap i6 is bolted to the front end-bracketit of the motor, by means of bolts 19. The center portion of the irontend-bracket I! also serves as the bearing-housing, being provided with asmall, shaft-encircling oil-reservoir space 23, which is filled with awick 22 which is preferably ;a multiple-strand, loose-twist, long-fibre,wool yarn of good quality. The wick-filled oilreservoir chamber 2! ofthe front bearing-assembly surrounds an oil-carrying collar 23 which iscarried by the shaft 4 adjacent to the outer end of the ball bearing 6,that is, the end of the ball bearing 8 which is'turthest away from themotor-rotor 2. The oil-carrying collar 23 is tapered or thickened, asindicated at 24, at its inner end, or the end adjacent to the ballbearing 6. The wick 22 passes through a window 25 into engagement withthe oil-carrying collar 23, so as to maintainathinfllmof oil onthiscollar,and

the tapered construction of the collar causes the strong centrifugalforce, resulting from the high speed of operation of the motor, to carrythe oll-film toward the tapered end, where it is "thrown oflf andvaporized, or converted into an oil-mist or spray, because of theextremely high speed ofoperation of the motor.

The oil-carrying collar 23 is'retained on the front end of the shaft 4by means of a nut 21- which may be locked in place by means of acotter-pin 28. The entire front end of the bear ing-assembly at thefront end of the motor is enclosed by means of an aluminum, magnesium orother light-weight metal bearing-cap 2! which is bolted to theend-bracket I by means of the previously mentioned bolts It. 7

The bearing-cap I, at the inside-end of the bearing-assembly at thefront end of the motor,

by "inside meaning at the end of the bearing i closest to themotor-rotor I, is provided with a re-entrant lnner end-portion 3| whichis shaped to provide close clearance with asteel oil-thrower 32 which ismounted on the shaft 4, so as to provide an oil-sealing means whichsubstantially prevents the escape of the oil-mist from thebearing-assembly, no matter in what position the motor operates. There-entrant inner end-portion 3| also serves as a cup to,hold any liquidoil that tends to escape when the shaft is vertical.

The front bearing-assembly and the rotorcore! are held in place on theshaft 4 by means of a steel core-retainer M which is disposed on theshaft 4, between the rotor-core 2 and the oil-thrower If, so that axialpressure is transwill be apparent that I have provided a solution forthe diilicult lubricating-problem which was presented in connection withmotors of'the illustrated class, which were required to operate atextremely high speeds, over an extremely wide range of outside-airtemperature-conditions,

, with the motor mounted in any possible position,

7 member II, I provide a'narrow, substantially 4 cylindrical,clearance-space or close-running seal continuous running.

and without re-lubrication during three weeks Experiments and actual usehave thoroughly demonstrated the successfulness of my lubricating means,to accomplish all of the intended purposes.

In accordance with my invention, the rear-end bearing-assembly isassociated with a dished, imperforate fan-supporting spider orair-guiding member 51 which is carried by the shaft 4 adjacent to-theoil-thrower 4!, said fan-member 5| carrying small, inwardly projectingfan-blades 52 which serve to create a movement of the air, or otherventilating fluid, within the motor-casing 3. As indicated by thearrows, the ventilating air for the motor is drawn into the casing 3through air-intakes 54 and 55 at the front end of the motor, anddischarged at air-outlets 56 at the rear end. Because of the extremelyhigh speed of operation of the motor, the fan 51-52 can be ofanextremely small size, as indicated.

In order to prevent the fan-suction from drawing the oil-mist out of therear-end bearingassembly which is close to the fan-supporting 58,between an intermediate portion 59 of the fan-supporting member SI, andan intermediate portion ii of the bearing-cap 36. For thesame purpose, Imay also provide a similar narrow, substantially cylindrical,clearance-space or. closerunning seal 63 between the outer end 64 of thefan-member II and an annular shoulder 65 which is provided on the rearend-bracket 38.

In order to further break up the fan-suction around the rear-endbearing-assembly, I provide a plurality of air-vent holes 61 and 68 inthe rear I end-bracket 38 and in the bearing-cap 36, so as ing-cap 36 isbolted to the rear endebracket 3.

of the motor, as indicated at 8!. The outer or rear end of the rear-endbearing-assembly is completed by a bearing-cap ll, of an aluminum,magnesium or other light-weight metal alloy, which is bolted to theend-bracket II by means of the aforesaid bolts 3!. The driving shaftend6 extends out'throughan opening I! in the L rear bearing-cap ll. Thisrear bearing-cap 4| to provide an air-communication from outside of themotor-frame 3 to a space 69 between the fan and the bearing, and betweenthe two close-running seals 58 and 83.

While I have described and illustrated my in vention in connection witha single illustrative form of embodiment, which is at present preferredby me, I desire it to be understood that is also shaped to provide asmall, shaft-encir- I cling oil-reservoir space I! which issubstantially filled with a wick II, as previously described for thefront end-bearing, said wick pressing, through a window 45, intoengagement with a tapered oil-carrying collar Ii which is pressed on theshaft 4, with the thick end of the collar 4' adjacent to the inner raceI! of the roller bearing H, so as to operate by delivering ayery smallquantity of oil, in the-form of a vapor or mist, to the bearing properII, as previously described in connection with the front end-bearing 6;The inner end of the bearing-cap 35 of the rear-end bearing-assemblyterminates in an inner portion: 48 which cooperates with a steel oil-ethrower 4! to provide a close-running oil-seal similar to the oil sealll-I! for the front endbearing.

From the construction thus far described, it

iii

such description and illustration are only illustrative, insofar as thebroader principlesof my invention are concerned, as various changes maybe made by those skilled in the art. I desire. therefore, that theappended claims shall be accorded the broadest construction consistentwith their language and the prior art.

I claim as my invention:

1. A combined bearing and ventilating assembly for one end of a machinehaving an enclosing, relatively stationary casing and an enclosed,relatively stationary stator-member therein, a relatively rotating shaftwhich is supported, at one end, in said combined bearing" andventilating assembly. and a rotor-member carried by said shaft incooperative relation to said statormember, said combined bearing andventilating assembly comprising a casing-supported bearinghousing havingits inner end-portion extendinginto a close-running oil-sealing relationto the member disposed in spaced relation to said inner end-portion ofthe bearing-housing, and a plurality of fan-blades projecting inwardlyfrom said fan-supporting member for causing a movement of a ventilatingfluid within the casing of the machine, said assembly beingcharacterized by a narrow, close-running clearance-space between aportion of said dished fan-supporting member and a part of saidbearing-housing for impeding the suction of the ventilating fluid fromsaid close-running oil-seal between said inner end-portion of thebearing-housing and the shaft,

and means for providing inlet-means for admitting ventilating fluidby-passing the bearing and communicating from outside of themachinecasing to a space between the fan-supporting .member and thebearing-housing, and between the narrow, close-running clearance-spaceand the close-running oil-seal.

2. A combined bearing and ventilating assembly for one end of a machinevhaving an enclosing, relatively stationary casing and an enclosed,relatively stationary stator-member therein, a relatively rotating shaftwhich issupported, at one end,- in said combined bearing and ventilatingassembly, and a rotor-member carried by said shaft in cooperativerelation to said statormember, said combined bearing and ventilatingassembly comprising a casing-supported bearinghousing having its innerend-portion extending into a close-running oil-sealing relation to theshaft, a lubricated, shaft-supporting bearingmember within saidbearing-housing, a shaftsupported, dished, imperforate fan-supportingmember disposed in spaced relation to said inner end-portion of thebearing-housing, and a plurality of fan-blades projecting inwardly fromsaid fan-supporting member for causing a movement of a ventilating fluidwithin the casing of by two separated, narrow, close-running clearformof an oil-vapor or mist, oil-sealing means for retaining the oil-vaporor mist within the bearing, said oil-sealing means including an innerend-portion of the bearing-housing extending vinto a close-runningoil-sealing relation to the shaft, a shaft-supported, dished,imperforate fansupporting member disposed in spaced relation to saidinner end-portion of the bearing-housing, and a plurality of fan-bladesprojecting inwardly from said fan-supporting member for causing amovement of a ventilating fluid within the casing of the machine, saidassembly being characterized by a narrow, close-running clearance-spacebetween a portion of said dished fan-supporting member and a part ofsaid bearing-housing for impeding the suction of the ventilating fluidfrom said close-running oil-seal between said inner end-portion of thebearing-housing and the shaft, and means for providing inlet-means foradmitting ventilating fluid by-passing the bearing and communicatingfrom outside of the machinecasing to a space between the fan-supportingmember and the bearing-housing, and between the narrow, close-runningclearance-space and the close-running oil-seal. I

4. A combined bearing and ventilating assembly for one end of a machinehaving an enclosing, relatively stationary casing and an enclosed,relatively stationary stator-member'therein, a relaance-spaces betweentwo diiferent portions of said dished fan-supporting member and twodifferent portions of said bearing-housing, respectively, for impedingthe suction of the ventilating fluid from said close-running oil-sealbetween said ixmer end-portion of the bearing-housing and the shaft, andmeans for providing inlet means for admitting ventilating fluidby-passing the bearing and communicating from outside of themachinecasing to the space between said narrow clearance-spaces.

3. A combined bearing and ventilating assembly for one end of a machinehaving an enclosing,

- relatively stationary casing and an enclosed, relatively rotatingshaft which is supported, at one end, in said combined bearing andventilating assembly, and a rotor-member carried by said shaft incooperative relation to said statormember, said combined bearing andventilating assembly comprising a stationary bearing-housing,-a bearingtherein, means within said bearinghousing for supplying oil to thebearing in the form of an .oil-vapor or mist, oil-sealing means forretaining the oil-vaporor mist within the bearing, said oil-sealingmeans including an inner end-portion of the bearing-housing extendinginto a close-running oil-sealing relation to the shaft, ashaft-supported, dished, imperforate fansupporting member disposed inspaced relation to said inner end-portion of the bearing-housing, and aplurality of fan-blades projecting inwardly from said fan-supportingmember for causing a movement of a ventilating fluid within the casingof the machine, said assembly being characterized 1 ferent portions ofsaid bearing-housing, respectively, for impeding the suction of theventilating fluid from said close-running oil-seal between said innerend-portion of the bearing-housing a bearing therein, means within saidbearinghousing for supplyingoil to the bearing in the a and the shaft,and means for providing ,inlet means for admitting ventilating fluidby-passing the space within the bearing-housing containing the oil-vaporor mist and communicating from outside of the machine-casing to thespace between said narrow clearance-spaces.

MICE O.

